Decalcomania for on-glaze decoration of ceramic ware

Abstract: A decalcomania for on-glaze decoration of ceramic ware is composed of mounting paper (1), adhesive (2) coated on the mounting paper (1), decorating material (3) laminated on the adhesive (2), and plastic coating (4) to hold the decorating material (3). In use, the decalcomania is stuck, with its mounting paper (1) peeled off, to the surface of the ceramic ware, followed by drying and firing. The decorating material (3) is composed of a plurality of layers (3a,3b,3c), with the upper layer being formed on the previously dried lower layer, such that it yields a layer with a total thickness of 300-2000 µm after firing. The decorating material in the lowest layer has a coefficient of thermal expansion which is close to that of the surface of ceramic ware and is also close to that of the decorating material in the adjacent layers. The plastic coating (4) is disposed between the uppermost layer (3c) of decorating material and the lowermost layer (3a) of decorating material.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a decalcomania for three-dimensional on-glaze decoration of ceramic ware such as whiteware, porcelain enamel, cloisonné, and glass. 2. Description of the Prior Art: Decalcomania for on-glaze decoration is usually composed of mounting paper, water-soluble adhesive coated thereon, decorating material laminated thereon, and plastic coating. To perform on-glaze decoration, it is stuck on the surface of ceramic ware, with the mounting paper peeled off, followed by drying and firing. If the decalcomania mentioned above is to be used for thick three-dimensional decoration on ceramic ware, it would be necessary to increase the thickness of the decorating material formed on the adhesive. However, the result is not as satisfactory as intended because of several problems. A thick decorating material does not readily dry in the production of decalcomania. It is difficult to accurately print a pattern of thick decorating material on the mounting paper. Thick build-up of decoration needs a large amount of expensive materials which flows during firing, resulting in a deformed pattern. There is a difference between the coefficients of thermal expansion of the decorating material and the body or glaze of ceramic ware, which causes cracking or peeling of the decorating material after firing. SUMMARY OF THE INVENTION It is an object of the present invention to provide a decalcomania for on-glaze decoration of ceramic ware, having at least some of the following advantages: It permits its decorating material to readily dry despite its thick build-up. It permits the effective use of the decorating material. It prevents the decorating material from flowing at the time of firing and also prevents the decorating material from cracking or peeling after firing. It affords a detailed three-dimensional pattern on ceramic ware. The present invention is embodied in a decalcomania for on-glaze decoration of ceramic ware which is composed of mounting paper, adhesive coated on the mounting paper, decorating material laminated on the adhesive, and plastic coating to hold the decorating material and which is used for decoration by sticking, with its mounting paper peeled off, to the surface of ceramic ware, followed by drying and firing, characterized in that the decorating material is composed of a plurality of layers, with the upper layer being formed on the previously dried lower layer, such that it yields a layer with a total thickness of 300-2000 µm after firing, the decorating material in the lowest layer has a coefficient of thermal expansion which is close to that of the surface of ceramic ware and is also close to that of the decorating material in the adjacent layers, and the plastic coating is disposed between the uppermost layer of decorating material and the lowermost layer of decorating material. The adhesive in the decalcomania can be a water-soluble paste or a fusible substance such as paraffin. DETAILED DESCRIPTION OF THE INVENTION The decalcomania of the present invention is constructed as follows: The decorating material is composed of a plurality of layers, preferably three or more layers, so that it is made thick. Each layer is formed after its lower layer has been formed and dried. As many layers as necessary are laminated in consideration of shrinkage due to drying and firing so that they yield a decorating layer which is 300-2000 µm thick after firing. Too thin a decorating material does not produce the effect of three-dimensional decoration. Too thick a decorating material presents difficulties in the manufacturing and firing processes and yields poor three-dimensional decoration. A preferred feature of the invention is that a desired pattern is formed only in the uppermost layer of decorating material. The other layers of decorating material are intended for volume increase and adjustment of the coefficient of thermal expansion. This eliminates the necessity of forming a desired pattern with a thick decorating material and of using a decorating material for the upper layer which has a coefficient of thermal expansion close to that of the surface of ceramic ware. After firing, the decorating material of the lower-most layer shrinks as the surface of ceramic ware shrinks and the decorating material of the other layers also shrinks as the decorating material of the adjacent layers shrinks. Therefore, it is necessary that the decorating materials of the adjacent layers have a similar coefficient of thermal expansion. This is achieved if the individual layers are arranged such that their coefficient of thermal expansion gradually increases or decreases in going from the lower layers to the upper layers or remains the same throughout all the layers. In addition, it is possible to make the lower layer thinner than the upper layer or to form the pattern such that the area of the decorating material (for each unit of pattern) gradually decreases in going from the lower layer to the upper layer. These provisions yield a three-dimensional decoration with a better appearance. The plastic coating disappears upon firing. It is necessary to hold the decorating material in place. It may be applied by brushing, spraying, or squeezing. According to the conventional technology, the plastic coating functions as a top coat (the uppermost layer) of the decalcomania for on-glaze decoration. This is not true of the present invention, in which the decorating material is made thick from a plurality of layers. In such a case, it is difficult to apply a plastic thin onto the entire layers. If a plastic is applied thick onto the entire layers to avoid incomplete covering, the result would be the flowing of the decorating material. According to the present invention, the plastic coating is disposed between the uppermost and lowermost layers of decorating material, preferably on the lowermost layer of decorating material. This permits the plastic coating to be formed thin between layers in the course of laminating the decorating material before the layers reach the maximum thickness. Incidentally, the decorating material of the uppermost layer may contain a coloring agent (such as pigment), and in such a case it is possible to obtain a three-dimensional decoration which is colored as desired. In addition, the decorating materials and plastic coating may be formed continuously by printing using a form, so that the decalcomania for on-glaze decoration can be produced efficiently using a simple apparatus. It is understood from the foregoing that the decalcomania for on-glaze decoration according to the present invention offers at least some of the following advantages: that the plastic coating can be formed easily, the thick layers as a whole can be dried with certainty, the decorating material hardly flows at the time of firing, the expensive decorating material can be effectively utilised, the decorating material hardly cracks or peels off after firing, and the decalcomania gives rise to an accurate three-dimensional decoration on the surface of ceramic ware. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of the decalcomania for on-glaze decoration pertaining to the present invention. The invention will be described with reference to the following examples. Example 1 A decalcomania as shown in Fig. 1 was prepared. It is composed of a mounting paper (1), a water-soluble paste (2), a first decorating material (3a), a plastic coating (4), a second decorating material (3b), and a third decorating material (3c), which are formed in layers on top of the other. The third decorating layer (3c) may contain a colouring agent in its surface to give a coloured pattern. The first decorating material was prepared by thorough mixing from 80 g of white frit (made by Yoshimura Ceramic Chemical) containing 65% lead oxide (PbO) and 20 cc of screen oil (made by Degussa in Germany) composed of 60% soluble acrylic resin and 40% diluent (50:50 mixture of xylene and terpene). It was applied to the paste-coated mounting paper (made by Isekyu in Japan) by printing with a 200-µm thick hand-cut stencil, followed by drying. The layer of the first decorating material was coated with the same resin as used in the above-mentioned screen oil by printing with a photographically prepared screen (1200-mesh, 100-µm thick fabric), in such a manner that the coating layer extends beyond the edge of the underlying layer. The second decorating material was prepared by thorough mixing from 78.4 g of white frit, 0.8 g of silica powder, 0.8 g of kaolin, and 20 cc of screen oil. (Silica powder and kaolin are intended to increase the coefficient of thermal expansion.) It was applied to the plastic coating by printing with a 350-µm thick hand-cut stencil. The third decorating material was prepared by thorough mixing from 77.6 g of white frit, 1.6 g of silica powder, 0.8 g of kaolin, and 20 cc of screen oil. It was applied to the layer of the second decorating material by printing with a 350-µm thick hand-cut stencil. The thus obtained decalcomania was dipped in water for 30-60 seconds to peel off the mounting paper and then stuck to the surface of a black solid-color tile, 10 cm square (made by Inax). After drying, the tile was fired in a furnace at 730-780°C. There was obtained a 600-µm thick, accurate white three-dimensional pattern. Flowing did not occur during firing, and cracking and peeling were not noticed after firing. The quality of decoration was comparable to that achieved with a sample in which the plastic coating is formed on the layer of the third decorating material. Example 2 Each of the first to fourth decorating materials was prepared from frit and screen oil in the same manner as in Example 1, said frit being composed mainly of 42% silica (SiO 2 ), 4.6% alumina (Al 2 O 3 ), 13% boron oxide (B 2 O 3 ), and 25.5% lead oxide (PbO). They were applied consecutively to the mounting paper in the same manner as in Example 1 by printing with a 300-µm thick hand-cut stencil. The plastic coating was formed by printing on the layer of the first decorating material. The thus obtained decalcomania was dipped in water to peel off the mounting paper and then stuck to the surface of a black solid-color tile, 10 cm square (made by Inax) in the same manner as in Example 1. After drying, the tile was fired in an electric furnace by heating up to 750°C over 5 hours and keeping at 750°C for 10 minutes, followed by slow cooling. There was obtained an 800-µm thick, accurate white three-dimensional pattern. Flowing did not occur during firing, and cracking and peeling were not noticed after firing. Example 3 The first decorating material was prepared by mixing screen oil with 95 g of frit and 5 g of titanium oxide in the same manner as in Example 1. The frit is composed mainly of 13% sodium oxide (Na 2 O), 6.4% alumina (Al 2 O 3 ), 66% silica (SiO 2 ), 4.5% potassium oxide (K 2 O), 8.9% zinc oxide (ZnO), and a small amount of boron oxide (B 2 O 3 ). The titanium oxide functions to impart a white color. The first decorating material was applied to the mounting paper in the same manner as in Example 1 by printing with a 200-µm thick hand-cut stencil. The layer of the first decorating material was covered with the plastic coating by printing. The second decorating material was prepared (in the same manner as above) by mixing screen oil with 80 g of frit (as specified above), 5 g of titanium oxide, and 15 g of Amakusa porcelain stone (to increase the coefficient of thermal expansion). It was applied to the plastic coating by printing using a hand-cut stencil in the same manner as above. The third and fourth decorating materials were prepared according to the same formulation as the second one. They were applied consecutively by printing with a 400-µm thick hand-cut stencil, such that the area of the layer of the third decorating material is smaller than that of the second decorating material and the area of the layer of the fourth decorating material is smaller than that of the third decorating material. The resulting decalcomania was tested in the same manner as in Example 2. There was obtained an 800-µm thick, accurate white three-dimensional pattern. Flowing did not occur during firing, and cracking and peeling were not noticed after firing. Example 4 The first to third decorating materials were prepared according to the formulation of the second decorating material in Example 3. The first decorating material was applied to the mounting paper by printing with a 200-µm thick hand-cut stencil. The layer of the first decorating material was covered with the plastic coating. The second and third decorating materials were applied consecutively by printing with a 400-µm thick hand-cut stencil, such that the area of the layer of the second decorating material is smaller than that of the first decorating material and the area of the layer of the third decorating material is smaller than that of the second decorating material. The fourth decorating material was prepared according to the formulation of the first decorating material in Example 3. It was applied by printing with a 200-µm thick hand-cut stencil. The resulting decalcomania was tested in the same manner as in Example 2. There was obtained an 800-µm thick, accurate white three-dimensional pattern. Flowing did not occur during firing, and cracking and peeling were not noticed after firing.

Claims: A decalcomania for on-glaze decoration of ceramic ware which is composed of mounting paper (1), adhesive (2) coated on the mounting paper (1), decorating material (3a,3b,3c) laminated on the adhesive (2), and plastic coating (4) to hold the decorating material (3) characterised in that the decorating material is composed of a plurality of layers (3a,3b,3c), with the upper layer (3c) being formed on the previously dried lower layer (3a), such that it yields a layer with a total thickness of 300-2000 µm after firing, the decorating material in the lowest layer (3a) has a coefficient of thermal expansion which is close to that of ceramic ware and is also close to that of the decorating material in the adjacent layers (3b,3c), and the plastics coating (4) is disposed between the uppermost layer (3c) of decorating material and the lowermost layer (3a) of decorating material. A decalcomania for on-glaze decoration of ceramic ware as claimed in claim 1, wherein the decorating material is formed in three or more layers (3a,3b,3c). A decalcomania for on-glaze decoration of ceramic ware as claimed in claim 1 or claim 2, wherein the layers (3a,3b,3c) of the decorating material are arranged such that their coefficient of thermal expansion increases or decreases gradually in going from the lower layer to the upper layer. A decalcomania for on-glaze decoration of ceramic ware as claimed in claim 1 or claim 2, wherein the layers (3a,3b,3c) of the decorating material have the same coefficient of thermal expansion. A decalcomania for on-glaze decoration of ceramic ware as claimed in any preceding claim, wherein the uppermost layer (3c) of the decorating material has a colouring agent in its surface. A decalcomania for on-glaze decoration of ceramic ware as claimed in any preceding claim, wherein the plastic coating (4) is disposed on the lowest layer (3a) of the decorating material. A decalcomania for on-glaze decoration of ceramic ware as claimed in any preceding claim, wherein the area of the layer (3a,3b,3c) of the decorating material (for each unit of pattern) gradually decreases in going from the lower layer (3a) to the upper layer (3c). A decalcomania for on-glaze decoration of ceramic ware as claimed in any preceding claim, wherein a desired pattern is formed only in the uppermost layer (3c) of the decorating material.

Inventors: KODAMA YUKIO, KODAMA, YUKIO
Applicants: KYOTO CERAMIC ART KYODOKUMIAI
Application year: 1994
Main classification: B44C1
IPC codes: B41M1, B44C1, C04B41